[Feature Request] Setting environment variables as build steps

Drone Support
1

I use drone with build on push from github. What I want to do is to push to staging whenever anything is pushed to master and to push to my production environment whenever anything is pushed to a branch called prod. What I want to do is to be able to set pipeline global env variables dynamically as a build step to be able to use them with variable interpolation. As an example:

pipeline:
  set_env_prod:
    environment:
       - env=production
    when:
      branch: prod
  set_env_staging:
    environment:
       - env=staging
    when:
      branch: master
  ecr:
    docker_image: blablabla:${env}
2

We are very conservative with adding new syntax to the YAML that is not part of the docker-compose specification, of which Drone is a superset. So the bar is generally high for this sort of YAML change.

For the use case described in this issue I don’t think a YAML change is required. If I wanted to setup this type of workflow it would be possible using the below configuration:

pipeline:
  build:
    image: golang
    commands:
      - go build
      - go test
  deploy_stage:
    image: plugins/ecr
    region: us-east-1
    access_key: xxxxxxx
    secret_key: xxxxxxx
    repo: xxxxxxx.dkr.ecr.us-east-1.amazonaws.com/foo
    tags: staging
    when:
      branch: master
  deploy_prod:
    image: plugins/ecr
    region: us-east-1
    access_key: xxxxxxx
    secret_key: xxxxxxx
    repo: xxxxxxx.dkr.ecr.us-east-1.amazonaws.com/foo
    tags: production
    when:
      branch: prod

If your goal is to keep things more DRY, you can do this using YAML anchors:

deployment: &deploy
  image: plugins/ecr
  region: us-east-1
  access_key: xxxxxxx
  secret_key: xxxxxxx
  repo: xxxxxxx.dkr.ecr.us-east-1.amazonaws.com/foo

pipeline:
  build:
    image: golang
    commands:
      - go build
      - go test
  deploy_stage:
    <<: *deploy
    tags: staging
    when:
      branch: master
  deploy_prod:
    <<: *deploy
    tags: production
    when:
      branch: prod

You can paste the above example into the online yaml parser to see how it works. http://yaml-online-parser.appspot.com/

3

Using YAML anchors is a very nice idea. Thanks!